MySQL读写分离是指让master处理写操作,让slave处理读操作,非常适用于读操作量比较大的场景,可减轻master的压力。
本文使用mysql-proxy实现mysql的读写分离,mysql-proxy实际上是作为后端mysql主从服务器的代理,它直接接受客户端的请求,对SQL语句进行分析,判断出是读操作还是写操作,然后分发至对应的mysql服务器上。对于多节点slave集群,还可以起到负载均衡的效果。
一、准备实验环境
MySQL的主从复制架构搭建详见http://9124573.blog.51cto.com/9114573/1785454
二、安装配置mysql-proxy
1、这里下载的mysql-proxy版本为mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit.tar.gz
# tar xf mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit.tar.gz -C /usr/local
# cd /usr/local
# ln -sv mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit mysql-proxy
# useradd -r mysql-proxy
[[email protected] ~]# tar xf mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit.tar.gz -C /usr/local/ [[email protected] ~]# ln -s /usr/local/mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit /usr/local/mysql-proxy [[email protected] ~]# cd /usr/local/mysql-proxy [[email protected] mysql-proxy]# ls bin include lib libexec licenses share [[email protected] mysql-proxy]# ls bin mysql-binlog-dump mysql-myisam-dump mysql-proxy [[email protected] mysql-proxy]# ls share/doc/mysql-proxy/ active-queries.lua commit-obfuscator.lua README tutorial-constants.lua tutorial-prep-stmts.lua tutorial-scramble.lua xtab.lua active-transactions.lua commit-obfuscator.msc ro-balance.lua tutorial-inject.lua tutorial-query-time.lua tutorial-states.lua admin-sql.lua COPYING ro-pooling.lua tutorial-keepalive.lua tutorial-resultset.lua tutorial-tokenize.lua analyze-query.lua histogram.lua rw-splitting.lua tutorial-monitor.lua tutorial-rewrite.lua tutorial-union.lua auditing.lua load-multi.lua tutorial-basic.lua tutorial-packets.lua tutorial-routing.lua tutorial-warnings.lua [[email protected] mysql-proxy]# useradd -r mysql-proxy
2、为mysql-proxy提供SysV服务脚本
# vim /etc/rc.d/init.d/mysql-proxy
...(内容略)
# chmod +x /etc/rc.d/init.d/mysql-proxy
# chkconfig --add mysql-proxy
[[email protected] ~]# vim /etc/rc.d/init.d/mysql-proxy ... [[email protected] ~]# chmod +x !$ chmod +x /etc/rc.d/init.d/mysql-proxy [[email protected] ~]# chkconfig --add mysql-proxy
3、为服务脚本提供配置文件/etc/sysconfig/mysql-proxy,内容如下所示:
# Options for mysql-proxy
ADMIN_USER="admin" #mysql-proxy的管理账号
ADMIN_PASSWORD="admin"
ADMIN_ADDRESS=""
ADMIN_LUA_SCRIPT="/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua" #完成mysql-proxy管理功能的脚本
PROXY_ADDRESS=""
PROXY_USER="mysql-proxy" #以什么身份运行mysql-proxy
PROXY_OPTIONS="--daemon --log-level=info --log-use-syslog"
其中最后一行,需要按实际场景进行修改,例如:
PROXY_OPTIONS="--daemon --log-level=info --log-use-syslog --plugins=proxy --plugins=admin --proxy-backend-addresses=192.168.30.10:3306 --proxy-read-only-backend-addresses=192.168.30.20:3306 --proxy-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua"
其中的proxy-backend-addresses选项和proxy-read-only-backend-addresses选项均可重复使用多次,以实现指定多个读写服务器或只读服务器;
rw-splitting.lua是实现读写分离功能的脚本文件
[[email protected] ~]# vim /etc/sysconfig/mysql-proxy # Options for mysql-proxy ADMIN_USER="admin" ADMIN_PASSWORD="admin" ADMIN_ADDRESS="" ADMIN_LUA_SCRIPT="/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua" PROXY_ADDRESS="" PROXY_USER="mysql-proxy" PROXY_OPTIONS="--daemon --log-level=info --log-use-syslog --plugins=proxy --plugins=admin --proxy-backend-addresses=192.168.30.10:3306 --proxy-read-only-backend-addresses=192.168.30.20:3306 --proxy-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua"
4、mysql-proxy命令的配置选项
我们也可使用mysql-proxy命令启动服务进程,其配置选项大致可分为帮助选项、管理选项、代理选项及应用程序选项几类:
--help
--help-admin
--help-proxy
--help-all #以上四个选项均用于获取帮助信息;
--proxy-address=host:port #代理服务监听的地址和端口
--admin-address=host:port #管理模块监听的地址和端口,默认为0.0.0.0:4041
--proxy-backend-addresses=host:port #后端读写mysql服务器的地址和端口;
--proxy-read-only-backend-addresses=host:port #后端只读mysql服务器的地址和端口;
--proxy-lua-script=file_name #完成mysql代理功能的Lua脚本;
--daemon #以守护进程模式启动mysql-proxy;
--keepalive #在mysql-proxy崩溃时尝试重启之;
--log-file=/path/to/log_file_name #日志文件名称;
--log-level=level #日志级别;
--log-use-syslog #基于syslog记录日志;
--plugins=plugin,.. #在mysql-proxy启动时加载的插件;
--user=user_name #运行mysql-proxy进程的用户;
--defaults-file=/path/to/conf_file_name #默认使用的配置文件路径;其配置段使用[mysql-proxy]标识;
--proxy-skip-profiling #禁用profile;
--pid-file=/path/to/pid_file_name #进程文件名;
5、创建admin.lua文件,将其保存至/usr/local/mysql-proxy/share/doc/mysql-proxy/目录中(略)
[[email protected] ~]# vim /usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua ...
6、启动mysql-proxy
service mysql-proxy start
网上都说mysql-proxy默认的代理服务端口是4040,本例中为3306,没有查到原因,有可能是新版本所做的更改;如果想使用其它端口,使用选项--proxy-address修改即可;
[[email protected] ~]# service mysql-proxy start Starting /usr/local/mysql-proxy/bin/mysql-proxy: [ OK ] [[email protected] ~]# netstat -tanp ... tcp 0 0 0.0.0.0:4041 0.0.0.0:* LISTEN 52446/mysql-proxy tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN 52446/mysql-proxy
7、管理mysql-proxy
mysql -u admin -h 192.168.30.14 -P 4041 -p
mysql> select * from backends; #查看后端mysql服务器状态
[[email protected] ~]# mysql -u admin -h 192.168.30.14 -P 4041 -p Enter password: ERROR 1045 (28000): password doesn‘t match [[email protected] ~]# mysql -u admin -h 192.168.30.14 -P 4041 -p Enter password: ... mysql> select * from backends; +-------------+--------------------+-------+------+------+-------------------+ | backend_ndx | address | state | type | uuid | connected_clients | +-------------+--------------------+-------+------+------+-------------------+ | 1 | 192.168.30.10:3306 | up | rw | NULL | 0 | | 2 | 192.168.30.20:3306 | up | ro | NULL | 0 | +-------------+--------------------+-------+------+------+-------------------+ 2 rows in set (0.00 sec)
三、测试
1、在主库上创建一个用户
grant select,insert,create,delete on *.* to [email protected]‘192.168.30.%‘ identified by ‘proxypass‘;
flush privileges;
该操作会同步到从节点,故无需再在从库上创建
2、准备抓包
# tcpdump -i eth0 -nn -XX ip dst host 192.168.30.10 and tcp dst port 3306
# tcpdump -i eth0 -nn -XX ip dst host 192.168.30.20 and tcp dst port 3306
3、连接mysql-proxy,进行读、写等操作
mysql -u proxytest -h 192.168.30.14 -P 3306 -p
经过测试发现:
所有写请求都被分发到主库,所有读请求被分发到从库;
从库不在线时,读请求被发往主库